Make sure fab semantics end up on top (#34512)

packages/flutter/lib/src/material/floating_action_button.dart

@@ -462,11 +462,9 @@ class FloatingActionButton extends StatelessWidget {
     );
 
     if (tooltip != null) {
-      result = MergeSemantics(
-        child: Tooltip(
-          message: tooltip,
-          child: result,
-        ),
+      result = Tooltip(
+        message: tooltip,
+        child: result,
       );
     }
 
@@ -477,7 +475,7 @@ class FloatingActionButton extends StatelessWidget {
       );
     }
 
-    return result;
+    return MergeSemantics(child: result);
   }
 
   @override

packages/flutter/test/material/floating_action_button_test.dart

@@ -763,6 +763,22 @@ void main() {
       paintsExactlyCountTimes(#clipPath, 0),
     );
   });
+
+  testWidgets('Can find FloatingActionButton semantics', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: FloatingActionButton(onPressed: () {}),
+    ));
+
+    expect(
+      tester.getSemantics(find.byType(FloatingActionButton)),
+      matchesSemantics(
+        hasTapAction: true,
+        hasEnabledState: true,
+        isButton: true,
+        isEnabled: true,
+      ),
+    );
+  }, semanticsEnabled: true);
 }
 
 Offset _rightEdgeOfFab(WidgetTester tester) {